Elastic yarn and method of making same



FeB. ll, 1936. N A 2,030,610

ELASTIC YARN AND METHOD OF MAKING SAME Filed May 22,' 1955 INVENTOR.

BY mar A TTORNEYS.

, 55 tion but rather will Patented Feb, ll, 1936 ELASTIC YARN AI METHOD OF MAKING AME Norman Elmer Randall, Shanock, R. I.

Application May 22,

6 Claims.

This invention relates to an elastic webbing; and has for one of its objects the provision of an elastic web which will have little or no creepage or contraction after it is finished and which ern the stretch as is usual in the manufacture of fabrics of this character at the present time.

Another object' of the invention is to 'exercise 15 control over the elastic strands as they are being Another object of the invention is the provision of an elastic fabric which will have a longer life than a fabric in which the elastic threads are under tension and stretched to a considerable 25 degree.

With these and other objects in View, the instruction, as will be more fully described, and particularly pointed out in the appended claims. 30 e In the accompanying drawing:

Fig. 1 is a top plan view of a fragmental portion of an elastic webbing incorporating my invention;

Fig. 2 is an elevation` or plan view 35 of the rubber core;

Fig. 3 illustrates this core as elongated during coverng; i

Fig. 4 is a view of a fragmental portion of a covered xstrand which is contracted after covering.

In the manufacture of elastic webbing, it is usual to cover the rubber strands while stretching the rubber strand to substantially its elastic limit, that is; if the rubber is capable of 500% 45 stretch, stretch will be given the rubof a section full 500% of-its original length and if it be desired "to produce the finished fabric which will have a 50 certain percentage of stretch less than 500%, say for instance 100% stretch, or there will be 50% contraction in the strand after covering, it is then arranged to coverr the naked elastic or rubber so that it cannot contract to its original posi- 'be continually under tension 1935, Serial No. 22,774 (CI. 117-34) tending to return to the length it was in the naked rubber state.- For example,` a one inch rubber if stretched 500% would become six inches long. If 100% elongation were desired, the covering would be arranged to permit contraction to 5 three inches and there be limited. The rubber core would constantly be tending to return to a one inch length. Other 'methods of controlling the stretch in the finished fabric were such as crowding into the i'abric during weaving a suflicient number of picks to control the stretch or to loom, V give just this 100% age of the stretch stretch and a larger percentprevented by reason of the their length so long as they have any life at all. A fabric so formed is found to creep or contract to a considerable extent, For instance, an average might be 15% to and this contraction will take place during hot or damp weather or while the fabric is worn on the body and subjected to the heat of the body and also during laundering. It is found that where a webbing is used to extend about the body, such for instance as in men's and women's underwear, and pyjamas, shorts, etc., that this creeping takes place to such an extent that the band about the .body becomes so tight as to be incomfortable due to shrinkage and much discussion exists to overcome this undesirable efiect. The problem has been solved in a woven fabric of strand rubber, as herein shown, and I have found that I can" control this stretch to such a degree that less 40 than 5% contraction will occur by following certain steps which are a radical change to those usually thought necessary to be employed in the preparing and weaving of acovered elastic thread; and to accomplish my result, I start with a' rubber strand and instead of elongating it 500% or to its limit as is usual, I elongate it from 150% to 200% and then wrap it in such a manner as to limit its further elongation and permit its `full contraction so that the rubber core is practically at restK and the same length as the naked rubber before wrapping. rthim weave the elastic strand in the customary manner. In this way, I may obtain a deflnite contraction of the fabric after it is woven, giving a desired definite stretch and the elastic wrp 'are substantially under no tension in the fabric or under so little tension that they are not constantly exerting that great pull or tension tending to contract, as h'as heretofore been present; and the following is a more detailed description ef the present embodiment 'of this invention, illustrating the pr'ferred means by which these advantageous results may be obtai'ned':

Withreference to the drawing, !0 designates a short section of the rubber core which for the sake of comparative purposes I have illustrated as one inch in length. This one inch section illustrates the naked rubber at rest or in other words, the rubber has no tendency to contract further than shown here in Figure 2. It will be understood that this naked rubber is of acontinuous length of many yards and that I am illustrating only one short section for the sake of comparison. This rubber core will be elongated about 150% or one inch will be extended to approximately two and one-half inches as illustrated in Figu'e 3, and covered with a suitable non-elastic covering ll. This covering, as applied, will limit the extensibility of the strand so that one inch of the naked rubber will never Stretch beyond the 150% or two and one-half inches in length. On the other hand, the covering is so arranged that the rubber' core will contract to substantially its naked rubber length or back to approximately one and one-tenth inches, such as shown at l2 in Figure 4. It willbe rea-. lized, however, that the rubber will not contract quite back to its original length in the naked state because of -the covering, but there will be no more than ten inches of covered rubber for every nine inches of naked rubber, which is quite in contrast to the heretofore usual condition of having about ten inches of covered rubber for every three to six inches of naked rubber.

After treating my rubber warp strands in this manner so that they may contract and come ubstantially to rest without any longitudinal tension, I weave them into a fabric in somewhat the usual manner, that is, the rubber or elastic strands are under full tension so that where 150% elongation is to be obtained as above pointed out, one inch of the naked rubber' after covered will be two and one-half inches but cannot Stretch further because of this covering. In such weaving, a

of course, there will be some restriction to the contraction due to the picks-placed across the warp strands,-perhaps 50% elongation will be taken out; however, instead of crowding in picks to limit the contraction, I place these picks in a rather loose manner so as not to limit the contraction but permit the rubber strands to contract to substantially their full extent and come back to a. position substantially at rest in the finished material after it leaves the roll of the loom. The fabric woven from the elastic strands having 150% stretch will have substantially elongation or stretch after weaving.

I have illustrated in Figura 1 a typical elastic webbing in which I have provided elastic strands !5, !6, l'l, !8,19, 20, 2| and 22 each consistirg of a rubber core covered in the manner above mentioned. The non-elastic threads in between these elastic strands are designated generally 23 and consist oi'. non-elastic Warn threads. The picks placed in the fabric are arranged to provide a one and one weave with the warp threads as at 24 between two closely adjacent rubber strands, while the"picks are arranged to'have a two and two weave with the warp threads as at 25 in the wider spaces between the groups of rubber strands. These wider spaces pucker as at 26 in a typical fabric as shown in Figure 1, when contracted.

This fabrid' isather loosely woven so far as the crowding ,of the picks is concerned, and will have 'a substantially 100% Stretch or any definite desred amount of stretch predetermined upon certain calculated Operations governed largely by the windiig of the rubber core, and yet' the rubber strands when the fabric is contracted will be substantially at rest and exert little or no pull in a longitudinal direction. By reason of the absence of longitudinalpull when contracted, the fabric will not shrink when exposed to the heat and sweat of the body or to laundering operations.

Further, a very flexible fabric is provided which is highly desirable for use where it is worn about the body, especially where an extended length is used such as on underwear, pyjamas or the like.

Further, when rubber which is porous is stretched a large percentage of. its mass is exposed to the action of the oxygen of the air and deterioration from the outside rapidly occurs while in the present fabric as the rubber is under no tension its pores are closed to a much greater degree and there is less opportunity forany such oxidation; thus, the life of the fabric formed as herein set forth is greatly increased.

It will of course be apparent that while I have referred to a fabric as made upon a loom that this invention may also be employed in fabrics which are braided, knitted or otherwise fabricated or put together, and I use the term woven or weaving in the claims in a broad sense to include the usual product from a loom or a braided or knitted structure'where the threads are intermeshed or interlaced one with the other.

The foregoing description is directed towards the method and Construction illustrated, but I desire it to be understood that I reserve the privilege of resorting to all the equivalent changes to which the Construction and method are susceptible, the invention being defined and limited` only by the terms of the appended claims.

I claim: 1. An elastic strand for fabrication comprising a rubber core and a non-elastic covering thereover, said rubber core being substantially at rest and of a length but slightly longer than the length of the naked rubber core uncovered, said covering being arranged to limit the extension of the strand to substantially the' extent of elongation as when the covering is applied, the same having a definite multiple of its length when at rest, said limit being substantially less than the limit of stretch of the naked rubber without a covering thereon.

2. An elastic strand for fabrication comprising a rubber core and a non-elastic covering thereover,'said rubber core being substantially at rest and of a length but slightly longer than the length of the naked rubber core uncovered, said covering being arranged to limit the extension of the strand to substantially the extent of elongation as when the covering is applied, the same having a definite multiple of its length when at rest, said limit being substantially less than the limit of Stretch of the naked rubber without a covering thereon, said covering compr'sing convolutions so spaced when the strand is stretched as to permit contraction of the elastic core to a substantially at rest position and at such contracted position substantially, completely enveloping the core.

&030310 3. 'Ihe method of preparing a covered elastic sti-and for fabrication which consists in stretching thecore to an extent substantialiy less than its elastic limit, then covering the elastic core to prevent any substantia further elongation thereof, said covering being disposed at such a helical pitch with its convolutions so spaced that the core may contract to substantially its naked state at rest when released with the covering practically completely enveloping'the'core when the core is at rest.

4. The method of preparing a covered elastic strand for fabrication which consists in stretching the core to an extent substatially` less than its elastic limit, then covering the elastic core to prevent any substantial further elongation thereof, said covering being disposed at such a helical pitch with its convolutions so spaced that the core may contract to substantially 'its naked state at rest when released. 4

5. The step in the method of preparing a subthe covering '3 stantially non-shrinking elastic rabric which consists in covering the elastic core of the strand to be used when under substantially less than its tull amount of stretch by helically disposing the covering at such a pitch as to limit the further extension o! the core but with its convolutions so spaced u to permit the core to return substantially to an at rest position and then weaving the strana in the fabrie in the usual manner.

8. An elastic fabric comprising interwoven threads some of said threads comprising a rubber core and a non-elastic covering thereover, said rubber core being substantially at rest and of a length but slightly longer than the length of the naked rubber core uncovered, said covering being arranged to limit the extension oi' the strand to substantially the extent of eiongation as when isapplied thereto, said limit being substantially less'than the limit of stretch of the naked rubber without a covering thereon.

' NORMAN ELMER RANDALL. 

